#include<iostream>
using namespace std;
void output(int n)
{
	if (n <= 2)
		cout << "1" << endl;
	else
	{
		long long p1, p2, p3;
		p1 = 1;
		p2 = 1;
		for (int i = 3; i <= n; i++)
		{
			p3 = p1 + p2;
			p1 = p2;
			p2 = p3;
		}
		cout << p3 << endl;
	}
}